1. Field of the Invention
The present invention relates to a liquid crystal display used in a display section of an electronic apparatus and, more particularly, to a reflective or reflective/transmissive liquid crystal display having a light-reflecting layer.
2. Description of the Related Art
Reflective/transmissive liquid crystal displays (transflective liquid crystal displays) have been developed in order to achieve preferable display both indoors and outdoors. A transflective liquid crystal display performs display utilizing light emitted by a backlight unit or external light from its surroundings such as sun light or light from a room lamp.
FIG. 6 shows a section of one pixel of a transflective liquid crystal display disclosed in Non-Patent Document 1. As shown in FIG. 6, the transflective liquid crystal display has two substrates 102 and 104 disposed to be opposite to each other and a liquid crystal layer 112 sealed between the two substrates 102 and 104. A plurality of source bus lines 106 (two of which are shown in FIG. 6) are formed on the substrate 102. Further, an insulation film 105 is formed throughout the substrate 102 so as to cover the source bus lines 106. A transparent electrode 108 is formed on the insulation film 105 substantially in the middle of the two source bus lines 106. The transparent electrode 108 transmits light emitted by a backlight unit (not shown) provided on the side of the substrate 102.
An acrylic resin layer 110 having irregularities on the surface thereof facing the substrate 104 is formed on the insulation film 105 excluding the region where the transparent electrode 108 is formed. The acrylic resin layer 110 is formed with a thickness that is substantially one half of the width of the gap between the substrates 102 and 104. Reflective electrodes 114 which follow the shape of the irregularities of the acrylic resin layer 110 are formed on the acrylic resin layer 110. The reflective electrodes 114 are electrically connected to the transparent electrode 108. The irregularities on the surface of the reflective electrodes 114 cause scatter reflection of light that impinges thereupon from the side of the substrate 104.
On the surface of the substrate 104 facing the substrate 102, a black matrix 116 formed in positions substantially opposed to the source bus lines 106, and a color filter (CF) layer 118 and a transparent electrode 120 formed throughout the substrate 104 are formed.
As shown in FIG. 6, each pixel of the transflective liquid crystal display has a reflective area in which a reflective electrode 114 having irregularities is formed and a transmissive area in which a transparent electrode 108 transmitting light from the backlight unit is formed. The transflective liquid crystal display is therefore capable of displaying an image utilizing light emitted by the backlight unit or external light such as sun light or light from a room lamp.
Transflective liquid crystal displays according to the related art have a problem in that they are very much expensive because a photolithographic process is used to form a reflective area. In order to reduce cost, the inventors developed a technique for forming a diffusing reflective electrode having wrinkly irregularities without using a photolithographic process, and combined the technique with a vertically aligned liquid crystal, and realized a reflective liquid crystal display having a high reflectivity and a high contrast ratio (see Patent Document 1). Further, the inventors developed a technique in which the orientation of wrinkly irregularities is controlled by providing a structure underlayer of the wrinkly irregularities layer (see Patent Document 2).
Patent Document 1: JP-A-2002-221716
Patent Document 2: JP-A-2003-215574
Non-Patent Document 1: IDW '99 Digest p. 183
Referring to FIG. 6, the transflective liquid crystal display must have a multi-gap structure in which the thickness of the liquid crystal layer 112 is varied to cause light to travel equal optical distances when it is transmitted by the liquid crystal layer 112 in the transmissive area and the reflective area. In order to achieve this, the acrylic resin layer 110 is formed with a thickness that is substantially one half of the width of the gap between the substrates 102 and 104, so that the beams of light transmitted by the liquid crystal layer 112 in the transmissive area and the reflective area travel optical paths having substantially the same length. However, there is no mention on how to control the thickness of the liquid crystal layer 112 between the substrates 102 and 104 of the transflective liquid crystal display where the thickness of the liquid crystal layer 112 varies between the same substrates.